Organic chemistry has a bad reputation; it is not uncommon for students to hear horrible stories about the difficulties they face before passing this exam. Although it is a complex matter, "organic chemistry" is basically not a nightmare as it is often portrayed. There is little information to memorize, but many processes to assimilate, therefore understanding the basics and a good study regime are the key to passing the exam.
Steps
Part 1 of 3: Basic Knowledge
Step 1. Learn the definition of "organic chemistry"
Generally speaking, this subject deals with the study of chemical compounds of carbon. Carbon is the sixth element of the periodic table and one of those necessary for life on Earth. Living things are made up of molecules which, in turn, are mainly composed of carbon. This means that organic chemistry also deals with the chemical processes that occur every day within organisms, plants, animals and ecosystems.
However, organic chemistry is not limited to living things. For example, it also studies the reactions that occur in the combustion of fossil fuels that fall within the scope of organic chemistry, since they are carbon-based
Step 2. Learn the most common ways to represent molecules
Organic chemistry has a decidedly more "graphic" approach than the general one. You often have to rely on molecule and compound drawings, more than you ever did in previous lessons. Understanding how to interpret these drawings is one of the most important basic skills for studying organic chemistry.
- Before starting, you need to familiarize yourself with Lewis structures. They are usually explained in the general chemistry part. According to this graphic representation, the atoms of a molecule are represented by their chemical symbol (the letter on the periodic table). The lines represent the bonds, the points the valence electrons. For a refresher, read this article.
- One method that is probably new to you for drawing molecules is the structural formula. With this graphic solution the carbon atoms are not written, but we are limited to the lines that identify the bonds. Since there are many carbon atoms in the study of organic chemistry, it is faster to draw the molecules. All atoms other than carbon are depicted with their own chemical symbol. You can do some research online to find some support for studying the structural formula.
Step 3. Learn how to draw links
Covalent bonds are by far the most common bonds that you will have to face during the organic chemistry course (even if a good knowledge of the ionic bond and the other genera is always essential). In a covalent bond, two atoms share unpaired electrons; if there are multiple unpaired electrons, then a double or triple bond is formed.
- In both structural and Lewis formulas, a single bond is represented by one line, a double bond by two lines, and a triple bond by three lines.
- In the structural formulas, the bonds between carbon (C) and hydrogen (H) are not drawn because they are very frequent.
- Except in special circumstances, atoms have only 8 valence electrons (on the outer orbital). This means that in most cases one atom can bond with at most four other atoms.
Step 4. Learn the basics of the three-dimensional representation of molecular structures
Organic chemistry requires students to think of molecules as they are in nature and not as a drawing on a paper. Molecules possess a three-dimensional structure. The nature of the bonds between the atoms is the most important factor that determines the 3-D shape of the molecule, although it is not the only one. Here are some things to remember when you are studying the three-dimensional shapes of carbon-based molecules:
- A carbon atom joined to four other single bonded atoms takes the form of a tetrahedron (a pyramid with four vertices). A good example for this structure is the methane molecule (CH4).
- A molecule with one carbon atom, joined to one atom with a double bond and two others with single bonds, has a planar triangular geometry (a flat triangle). The CO ion3-2 is an example.
- A molecule composed of a carbon atom, joined to two atoms through double bonds or joined to a group with a triple bond, assumes a linear geometry (a rigid line). The carbon dioxide molecule (CO2) is an example.
Step 5. Learn to decipher orbital hybridization
While the name is intimidating, it is not such a difficult concept to understand. In practice, hybrid orbitals are the method by which chemists represent the valence electrons of an atom based on how the atom behaves (rather than how it is drawn). If an atom has a certain number of unpaired electrons available to create bonds, but they tend to form a different number of bonds, then to describe this difference it is said that the atom has hybrid orbitals.
Carbon is a perfect example of this kind of atoms, as it has four valence atoms: two in the 2s orbital and two unpaired in the 2p orbital. Since there are two unpaired electrons, one might expect carbon to form two bonds. However, practical experience teaches us that the coupled electrons in the 2s orbital form bonds even if they are not unpaired. Thus it can be said that a carbon atom has four unpaired electrons in its sp hybrid orbital
Step 6. Learn the basics of electronegativity
In organic chemistry there are many factors that determine how two molecules react with each other; electronegativity is one of the most important. This concept measures how "forcefully" the atom holds its electrons. Atoms with high electronegativity retain electrons with greater force (and vice versa for low electronegativity atoms). You can refer to this article for more details.
- As you move to the right and upwards along the periodic table, the electrons become more and more electronegative (excluding helium and hydrogen). Fluorine, the element in the upper right, is the one with the highest electronegativity.
- Since electronegative atoms "tend to attract" other electrons, they react by "taking" available electrons in other molecules. For example, atoms like chlorine and fluorine often appear as negative ions, because they have taken electrons from other atoms.
Part 2 of 3: Study Tips
Step 1. Don't be intimidated
This subject introduces many new concepts and forces you to think about chemical problems from a different perspective; in addition you will have to learn a whole new "chemical vocabulary". Relax, all your classmates face the same problem. Study diligently, ask for help in case of need and you will see that everything will be fine.
Do not be frightened by the "horror stories" of students who passed the chemistry exam before you. It is typical of boys to always "inflate" their experiences a little. If you go to your first exam when you are terrified and convinced that you are facing an impossible task, then you will make everything more complicated than it really is. On the contrary, you should strengthen your confidence by studying a lot and resting the night before the exam
Step 2. Try to understand the concepts instead of memorizing them
During the lessons hundreds of chemical reactions will be examined. It's practically impossible to memorize them all, so don't waste your time and limit yourself to only the most important ones. Focus on the basic principles that govern the most common reactions; most only follow one or two patterns, so knowing the latter and knowing how to apply them becomes a much more efficient technique for solving chemistry problems correctly.
However, if you have a good memory, you can use this skill to your advantage. Try writing the mechanics of fundamental reactions on flashcards and use them to memorize them. You will still need to be able to cope with a reaction you have never seen, but you can use the same principles to develop the correct mechanism
Step 3. Learn the functional groups
Basic organic chemistry uses the same set of structures in virtually all molecules; these structures are known as "functional groups". Knowing how to identify and understand how they tend to react is a fundamental step in solving organic chemistry problems. Since functional groups constantly react in the same way, knowing their characteristics allows you to solve a wide range of problems.
In organic chemistry, there are too many functional groups to list them in this article. However, it is not difficult to find sources on the internet that can help you in this regard. In this link you have an example
Step 4. If in doubt, follow the flow of electrons
At a basic level, most organic chemistry reactions involve two or more molecules exchanging electrons. If you can't figure out how to trigger the reaction mechanism, begin to consider where you might sensibly move the electrons. In other words, look for atoms that look like good electron “receivers” and those that are more likely to give them away. Perform the shift and then ask yourself "what do you have to do to bring the molecules to a state of stability".
For example, since oxygen (O) is more electronegative than carbon, the O atom joined to C with a double bond in the carbonyl group tends to retain the bond electrons closest to itself. This gives C a slight positive charge and makes it a good candidate to receive electrons. If there is an atom in the reaction that tends to release electrons, then it makes sense to connect it to C, forming a new bond and triggering the reaction
Step 5. Form a study group for homework and exams
You don't have to feel like you're alone against organic chemistry. Doing homework with other friends following the same course is a great idea. Not only can others help you with the concepts that are most abstruse to you, but you can also internalize more those you have already understood by re-explaining them to your companions.
Part 3 of 3: Seeking Help
Step 1. Get to know the professor
This is the person who knows the subject best in the classroom. Take advantage of this very valuable resource. Go to his studio to discuss concepts you didn't understand. Try to ask him a few clear and concise questions, or ask him a couple of problems that you can't solve. Be prepared to have to explain the process that leads you to the wrong solution.
- Avoid going to your teacher without a clear idea of what you want. Simply stating that you haven't done your homework isn't helpful.
- This is not only a great opportunity to find answers to your doubts, but also a way to get to know your teacher. Remember that if you want to access a master's or PhD, you will also need his references. Teachers are willing to write positive notes to students who have taken the time to talk to them.
Step 2. Use tools to help you visualize the problem
In organic chemistry the shape of molecules determines how they react. Since it is difficult to make a three-dimensional graphical representation of complex molecules, you can use physical elements, such as children's constructions, to analyze complicated structures.
- Molecular model kits allow you to build molecules out of plastic pieces. They could be quite expensive if you buy them at a college bookstore or lab supply store; however, some teachers lend them free to students who request them.
- If you can't get a "real" kit, use foam balls, markers, and wooden pins. You can easily find them in home improvement and fine art stores.
- There are also several computer graphics programs that help you visualize molecules in 3-D. Follow this link (in English) for an example.
Step 3. Join an online forum
One of the lifelines in the turbulent sea of organic chemistry is the high number of students who seek and offer help online. There are many forums made up of a large community of people who want to discuss more complicated topics. Try posting a problem that you can't solve and work with the people who will answer you to find the solution.
Virtually every university with a chemistry faculty has its own online page or forum organized by students and which aims to help each other. It won't be hard to find the right online community for you
Step 4. Test the online resources
There are many sites that help you solve the most complex issues of organic chemistry. Here are some of them (in English):
- Khan Academy: You can find numerous lecture videos covering the basic topics.
- Chem Helper: on this site there are links to exam simulations, help forums, reaction mechanisms and much more. You will also find a section for the laboratory.
- University of South Carolina Aiken: You will find a list of various useful sites covering many organic chemistry topics.
Advice
- The more you study organic chemistry, the more you will be able to internalize the most important concepts. Try to dedicate at least an hour or two every day to this subject; the quality of the study is just as important as the quantity.
- A good knowledge of basic physics is of great help in understanding the numerous topics of organic chemistry. If possible, also take physics classes before enrolling in the chemistry course.
- In this section of wikiHow you can find many useful articles.
